The Bodélé depression: a single spot in the Sahara that provides most of the mineral dust to the Amazon forest

About 40 million tons of dust are transported annually from the Sahara to the Amazon basin. Saharan dust has been proposed to be the main mineral source that fertilizes the Amazon basin, generating a dependence of the health and productivity of the rain forest on dust supply from the Sahara. Here we show that about half of the annual dust supply to the Amazon basin is emitted from a single source: the Bodélé depression located northeast of Lake Chad, approximately 0.5% of the size of the Amazon or 0.2% of the Sahara. Placed in a narrow path between two mountain chains that direct and accelerate the surface winds over the depression, the Bodélé emits dust on 40% of the winter days, averaging more than 0.7 million tons of dust per day.

Even understanding how connected the global ecosystem is, research like this provides amazing reminders of those connections.

The 2009 Programme for International Student Assessment (PISA)* report has been released. The report examines the science of 15 year olds from 57 countries in math, science and reading. The main focus of PISA 2009 was reading. The survey also updated performance assessments in mathematics and science.

The Asian countries continue to do very well for several reason including tutoring; they have even turned tutors into rock stars earning millions of dollars. The results show that the focus on student achievement in sciences has had an impact in Asia.

The emphasis is on mastering processes, understanding concepts and functioning in various contexts within each assessment area. the PISA 2012 survey will return to mathematics as the major assessment area, PISA 2015 will focus on science.

Results for the Science portion (rank – country – mean score)(I am not listing all countries):

The complete asexuality of a widespread fungus-gardening ant, the only ant species in the world known to have dispensed with males entirely, has been confirmed by a team of Texas and Brazilian researchers.

Most social insects—the wasps, ants and bees—are relatively used to daily life without males. Their colonies are well run by swarms of sterile sisters lorded over by an egg-laying queen. But, eventually, all social insect species have the ability to produce a crop of males who go forth in the world to fertilize new queens and propagate.

“Animals that are completely asexual are relatively rare, which makes this is a very interesting ant,” says Rabeling, an ecology, evolution and behavior graduate student at The University of Texas at Austin. “Asexual species don’t mix their genes through recombination, so you expect harmful mutations to accumulate over time and for the species to go extinct more quickly than others. They don’t generally persist for very long over evolutionary time.”

Previous studies of the ants from Puerto Rico and Panama have pointed toward the ants being completely asexual. One study in particular, by Mueller and former graduate student Anna Himler (now at Arizona State University), showed that the ants reproduced in the lab without males, and that no amount of stress induced the production of males.

Scientists believed that specimens of male ants previously collected in Brazil in the 1960s could be males of M. smithii. If males of the species existed, it would suggest that—at least from time to time—the ants reproduce sexually.

Rabeling analyzed the males in question and discovered that they belonged to another closely related (sexually reproducing) species of fungus-farmer, Mycocepurus obsoletus, thus establishing that no males are known to exist for M. smithii. He also dissected reproducing M. smithii queens from Brazil and found that their sperm storage organs were empty.

Taken together with the previous studies of the ants, Rabeling and his colleagues have concluded that the species is very likely to be totally asexual across its entire range, from Northern Mexico through Central America to Brazil, including some Caribbean islands.

As for the age of the species, the scientists estimate the ants could have first evolved within the last one to two million years, a very young species given that the fungus-farming ants evolved 50 million years ago.

Rabeling says he is using genetic markers to study the evolution and systematics of the fungus-gardening ants and this will help determine the date of the appearance and genetic mechanism of asexual reproduction more precisely in the near future.

Recently-discovered Amazonian settlements could be a new type of metropolis, unseen elsewhere in the world and hidden until recently in the Kuikuro jungle, say anthropologists.

Revealed by overgrown earthworks, the 100 square-mile urban units consist of clusters of interconnected villages ranging from 50-150 acres in size. The town-nodes were arranged along a highly-regular pattern of roads built around a central plaza about 500 feet across. The cities appear to have been at their height between the 13th and 17th centuries.

“No single Xingu settlement merits the term ‘city.’ But what do you do with a core of five settlements are few kilometers away from each other?” Michael Heckenberger, a University of Florida anthropologist currently in Brazil, told Science. “A fast walk from one to another would take you 15 minutes, maximum.”

The Webometrics Ranking of World Universities provides another estimate of the top universities. The methodology is far ideal however I still find it interesting. The various attempts to rank schools can provide a general idea of impact of various institutions (though the measures are fairly crude). Still a sensible picture (especially at the country level) can emerge. And the various rankings should be a able to track shifts in the most influential institutions and relative country strength over time. How quickly those rankings track changes will vary depending on the measures used. I would imagine most will lag the “real” changes as it is easy to imagine many measures that would lag. Still, as I have said before, I expect the USA will lose in relative ranking compared to China, India, Japan, Singapore, Mexico…

The ranking methodology used here weighed rankings in: Jiao Tong academic rankings, Essential Science Indicators, Google Scholar, Alexa (a measure of web site visits to universities) and The Times Higher World University Rankings.

Country representation of the top universities (number of top schools in each country):